Bacteria, fungi, viruses, algae and other microorganisms are always present in our environment. Such microorganisms are frequently an essential part of ecological systems, industrial processes, and healthy human and animal bodily functions, such as digestion. In other instances, however, microorganisms are highly undesirable as a cause of illness, odors and damage or destruction of a wide variety of materials.
The species and numbers of microorganisms present vary depending on the general environment, on the nutrients and the moisture available for the growth of the microorganisms, and on humidity and temperature of the local environment. Nutrients for microorganisms abound in the normal environment. Furthermore, many materials, including plastic coatings and objects, wood, paper and other natural fibers can serve as nutrients for microorganisms which will degrade those materials. In addition, certain bacteria are capable of remaining viable in a dormant state on floors or on objects for long periods of time until they are deposited in the proper media for growth. Consequently, potentially harmful microorganisms can be transported merely by walking on floors, brushing against walls or furniture or by handling objects.
It is well recognized that a major difficulty in health care facilities is the spread of infectious diseases caused by a wide variety of microorganisms. The problem is exacerbated in these facilities because many of the patients are in a weakened condition or immunosuppressed. One of the most common means by which these organisms are spread is health care personnel. Another important source of infection are the floors, furniture and other plastic objects routinely used in these settings. Conventionally, the plastic products in these facilities are periodically cleaned with strong disinfecting cleansers to remove or kill accumulated microorganisms. Between cleanings, however, it is possible for the plastic products to constitute a major vector for cross-infection or spread of infections diseases.
Pathogenic microorganisms can also be deposited on fabrics such as towels, clothes, laboratory coats and other fabrics where they remain viable for long periods of time. When the microorganisms grow on or in a plastic product, fiber, or fabric, they form unsightly colonies and can eventually break down the plastic, fiber, fabric, or other material. Washing with conventional detergents does not always kill or remove the microorganisms.
The control of microbial growth is a major problem in both industry and the home. It has proved difficult, however, to develop a microbiocidal composition that is effective in controlling the growth of a wide variety of unwanted microorganisms and is, at the same time, safe for use around human beings and animals. Another difficulty is the extreme variability of response of various microorganisms to conventional microbiocidal agents. Even within bacteria, Gram-negative and Gram-positive bacteria respond differently to antibiotics. Further, the antibiotics that are effective against procaryotic organisms are usually ineffective against eucaryotic microorganisms such as fungi and yeasts.
U.S. Ser. No. 047,561 entitled "Microbiocidal Composition and Method of Preparation" filed Apr. 27, 1987 by Robert H. McIntosh disclosed a broad spectrum, safe, biocidal composition having the following general formula: ##STR1## wherein R and R' are an alkyl, aryl, aralkyl or alkaryl group, one of R or R' can be H, X is a Group I metal ion, Group II metal ion, transition metal ion, or an organic ion such as an ammonium ion, and there is at least one free hydroxyl group. Examples of the alkyl, aryl, aralkyl and alkaryl include straight chains, branched chains or cyclic alkyl groups having from 2 to 24 carbon atoms, polyoxyethylene or polyoxypropylene having from 2 to 12 ethylene oxide or propylene oxide units respectively, alkyl phenoxy polyoxyethylene containing from 2 to 12 ethylene oxide units, alkyl phenoxy polyoxyethylene containing ethylene oxide units and from 2 to 24 carbon atoms in the phenolic alkyl chain, or a polyhydroxy compound such as ethylene glycol, glycerol, or sorbitol. The positively charged ion does not appear to be essential for biocidal activity against all types of organisms, although the charge of the phosphate ester does affect the degree of biocidal activity. The relative ratios of mono-and di-esters also appears to affect the antimicrobial activity. As used herein, the general compound is referred to as a "phosphate ester". When the salt is specifically required or utilized, the compound is referred to as a "phosphate ester salt".
This compound has previously been demonstrated to be effective when incorporated into epoxy resins, combined with a surfactant for use as an antimicrobial detergent, used as a coating for fabric, wood or plastics, or a preservative when applied to an absorbent material. Despite the successful use of these compounds in a variety of ways, there remains a need for a means of incorporating the compounds into polymeric materials which results in effective antimicrobial control over an extended period of time, wherein the unbound phosphate ester or salt is not extensively removed by washing and surface wear. Further requirements for such a system are that it cannot decrease the stability and biocidal activity of the phosphate compounds.
Accordingly, it is an object of the present invention to provide the biocidally effective phosphate esters in combination with carrier materials to yield products having biocidal properties which are resistant to washing and wear over an extended period of time.
Another object of the present invention is to provide methods for incorporating the biocidally effective phosphate esters into carrier materials which are relatively easy and inexpensive.
A further object of the present invention is to provide methods and means for the application of the biocidally effective phosphate esters to the surface of both synthetic and natural fibers, fabrics and fibrous surfaces to thereby impart biocidal properties to the materials which are resistant to washing.